The invention relates to a method to clean a surface polished by chemical mechanical polishing (CMP). CMP is used in the fabrication of semiconductor devices to produce a planarized surface.
Typical uses of CMP include planarizing a deposited interlevel dielectric before forming a metal wiring layer on the ILD; or forming a tungsten plug by filling a contact hole etched in dielectric, then planarizing the tungsten overfill, leaving tungsten only in the hole.
During formation of some monolithic three dimensional memory arrays, a dielectric material covers patterned tungsten features, then the dielectric material is subjected to CMP to expose the tungsten features. Exposing tungsten or a like material during dielectric CMP is not conventional. After such a CMP step is completed, it may be found that slurry particles remain adhering to the polished dielectric material. These particles are resistant to usual cleaning techniques.
There is a need, therefore, for a low-cost, reliable method to remove slurry particles from a surface of coexposed tungsten and dielectric following a dielectric CMP step.